A portable endoscope has a pump, a tank that stores liquid, a first coupling tube that spatially connects the pump with a gas supplying tube, a divergent tube that diverges from the first coupling tube and extends toward an inside of the tank, a balloon that is spatially connected to the divergent tube and is expandable and shrinkable in the tank, a second coupling tube that spatially connects the inside of the tank with a liquid supplying tube, and a gas direction controller that selectively directs the gas discharged from the pump to one of the gas supplying tube and the divergent tube. The liquid is stored outside of the balloon. The tank includes a sealing member that hermetically seals the tank.